EXPERIMENTAL IRRADIATION The Experimental Irradiation core provides for the use of radiation by the members of the University of Michigan Comprehensive Cancer Center. The services of this core are critical to users in the UMCCC, serving not only those interested in radiation biology and radiation therapy but also those for whom radiation is a tool. Thus, the facility serves a primary goal of the Cancer Center, supporting basic research and it translation to clinical applications. The irradiation core not only maintains and operates the irradiators but also consults with each investigator before initiation of a project so that the studies are carried out in the most efficient way possible. The experience of the director and manager allow them to offer investigators information on dosage and treatment regimens, particularly in animal studies, so that experimental resources are not wasted. Also, their experience allows them to foster interactions, because they connect investigators who have used radiation in various types of experiments over the last several years. Use of the Experimental Irradiation core by a wide variety of members of the Cancer Center is exemplified by the distribution of users. The 33 Cancer Center members who utilize the core participate in 12 Programs including Breast Oncology, Cancer Cell Biology, Molecular Therapeutics, Gastrointestinal Oncology, and Radiation Sciences, among others. In order to provide this vital service, the core maintains three irradiators. The primary irradiator is a Pantak Therapax DXT 300 orthovoltage unit which is used for irradiations of cell cultures and animals (primarily mice and rats, but also available for use with rabbits and dogs, as needed). The core maintains two 137-Cs irradiators. One is devoted to animal irradiations and is located in the specific pathogen free area of the mouse housing facility in ULAM. The availability of this unit allows investigators to perform irradiations without removing their immunodeficient mice from the quarantined facility. The other irradiator is for low dose rate (0.1-0.4 Gy/hour) irradiations. This irradiator, located within the Radiation Oncology department in the 1331 Ann Bldg is built inside a humidified incubator, permitting studies of chronic exposure to very low radiation doses.